Tile set texture seams in forward rendering

I'm wondering if someone would have some insight on what is happening here. I'm importing a mesh into Unity that consists of faces UV mapped onto a hand authored pixel art tile set, with the tiles sitting right next to each other.

In this image, the seams are most apparent around the window.

When using forward rendering, the seams between the faces are apparent. When using deferred rendering, the seams don't appear.

Deferred rendering is an okay workaround but I don't really want the performance cost. Using the half texel offset described in the page above does not look good at pixel art scales.

Ideally I'd be able to fix it with a shader but I'm not quite sure where to even start. I can write shaders, and it seems like maybe an alpha channel sampling weirdness but from what I know of the default Unity shaders they don't actually use a separate alpha channel.